MI service gas mask (United States)
|image = Sup bro.jpg|country = |period = 1921-1944|issued = }} Development Conception The Model of 1919 Gas Mask originated in World War I and was an improvement over the Akron Tissot masks. It was far easier to produce. The Model of 1919 and the Akron Tissot masks eliminated the nose clip and mouthpiece of the WWI CE and RFK type box respirators. The problem of lens fogging was reduced by directing the incoming air over the eyepieces. A flutter valve controlled outlet from the mask. Towards the end of World War I the army was looking to improve upon the model of 1919 gas mask. In 1920 a new type of carrier was standardized known as the model of 1920 Carrier or the MII. This new type of carrier was meant for filters with inlet valves located on the top of the filter. A new type of mask configuration was also being developed using a model of 1919 facepiece with a 27-inch hose with an MI felt filter with this new carrier. The US Army ultimately decided to completely re-work the model of 1919 Design changes. These changes were with the angle tube assembly, the deflector system, and larger lens crimpings. The facepiece was assembled using a flat sheet of brown gum rubber with a stockinette vulcanized onto the sheet rubber. The rest of the hardware i.e lens crimpings was added afterwards. The final step was the facepiece being joined together at the chin. This new facepiece would be standardized in 1921 as the MI-I-II service gas mask. The mask was issued in five different sizes. First changes Sometime in the mid-20s there was an alteration made to the head harness. The MI used an MI head harness which was adjusted from the head pad. This new type of head harness was adjusted from the facepiece and would be standardized as the MII head harness. No further changes were made until the MIA1 Service gas mask. MIAI In 1928 the first alteration to the facepiece was made resulting in threaded lenses so the lenses could be replaced. This new Facepiece would also be issued with a new filter known as the MIV which had an inlet valve on the bottom rather than the top like the MI felt filter. A new carrier was issued known as the MIII. it was strictly meant for filters with inlet valves on the bottom of the filter. MIA2 In 1934 the second alteration was made resulting in the lower harness tab being lengthened. It was made in a universal size with the face piece being made of a black natural rubber rather than gum rubber like the MI and MIA1 facepieces. This new facepiece was issued with a new filter as well as a new carrier. The filter that was issued was the MIXA1 and the carrier was a MIV. Some of the later production MIA2 masks were also issued with MIVA1 carriers. Last uses and packaging of the masks By 1937 Edgewood Arsenal was producing over 50,0000 MIA2 masks per year. In 1941 the MI service mask was a limited standard, the MIA1 was a standard in size 1, and the MIA2 was a standard. The MI series masks (MI, MIA1, MIA2) were in service until 1944 and were declared obsolete by the end of the war.In storage the masks were packaged into A metal can. Early on the MI and MIA1 Service gas masks Gas mask were stored in a MI tin. Later on the later production MIA1s and MIA2 Service masks were stored in a MII tin. The reason for this it would keep the masks from getting damaged and kept moisture out of the filters. Carriers The MI service series were issued with four types of carriers. They were the MII, MIII, MIV, MIVA1. The carriers would be worn at the hip with a waist and shoulder strap. The MII used filters with inlet valves located at the top. The MIII had the exact same design as the MII but used filters with inlet valves located at the bottom. The MIV was modified with a tab located on the lower part of the carrier to make it easier to close. The MIVA1 added 4 additional inches to the waist strap but was otherwise identical to the MIV. Markings The MI and MIA1 had the letters US imprinted on the forehead. They also included the size number under the US. The MIA2 mask was stamped US with a U for Universal under the US. Filters The filters were replaced with improved models over the years. The MI service gas mask was first issued with the blue MI felt filter. The inlet valve was located at the top. The MIA1 was issued with the MIV filter which was an OD green color and had the inlet valve located at the bottom. The MIXA1 is an OD green cannister that was crimped at the top rather than using tape to hold it together like the MI and MIV. Category:United States Category:Military Gas Masks Category:World War II Era Mask Category:Full Face Masks Category:Interwar Era Mask